Concentration Gradient-Driven Aluminum Diffusion in a Single-Step Coprecipitation of a Compositionally Graded Precursor for LiNiCoAlO with Mitigated Irreversibility of H2 ↔ H3 Phase Transition.

LiNiCoAlO (NCA) possessing a nano-/micro hierarchical architecture delivers a high specific capacity of 200 mAh/g with an upper cutoff voltage of 4.4 V. However, the structural reconstruction due to the irreversibility of the H2 ↔ H3 phase transition at higher voltage increases the initial irreversible capacity loss and charge-transfer impedance and reduces the performance at higher C-rates.